Straddled vehicle

Abstract

A straddled vehicle, including: a vehicle body frame; a steering device rotatably supported by the vehicle body frame; a front wheel that is steered by the steering device to thereby change a steering angle of the front wheel; a first detection device that detects at least one of a steering angular velocity of the front wheel, an acceleration of the steering angle of the front wheel, and a steering torque of the front wheel; a restriction device that is configured to restrict a change in the steering angle of the front wheel; and a controller that causes the restriction device to restrict a change in the steering angle of the front wheel when a value detected by the first detection device is equal to or greater than a predetermined value.

What is claimed is: 
     
         1 . A straddled vehicle comprising:
 a vehicle body frame;   a steering device rotatably supported by the vehicle body frame;   a front wheel that is steered by the steering device to thereby change a steering angle of the front wheel;   a first detection device that detects at least one of a steering angular velocity of the front wheel, an acceleration of the steering angle of the front wheel, and a steering torque of the front wheel;   a restriction device that is configured to restrict a change in the steering angle of the front wheel; and   a controller that causes the restriction device to restrict the change in the steering angle of the front wheel when a value detected by the first detection device is equal to or greater than a predetermined value.   
     
     
         2 . The straddled vehicle according to  claim 1 , wherein
 when the value detected by the first detection device is smaller than the predetermined value, the controller causes the restriction device to allow the change in the steering angle of the front wheel.   
     
     
         3 . The straddled vehicle according to  claim 1 , wherein
 the controller causes the restriction device to allow the change in the steering angle of the front wheel when the straddled vehicle is traveling straight, and the value detected by the first detection device is equal to or greater than the predetermined value, and   the controller causes the restriction device to restrict the change in the steering angle of the front wheel when the straddled vehicle is turning on a curve, and the value detected by the first detection device is equal to or greater than the predetermined value.   
     
     
         4 . The straddled vehicle according to  claim 1 , further comprising a speed detector that detects a speed of the straddled vehicle, wherein
 the controller causes the restriction device to restrict the change in the steering angle of the front wheel when the speed detected by the speed detector is higher than a threshold speed, and the value detected by the first detection device is equal to or greater than the predetermined value, and   the controller causes the restriction device to allow the change in the steering angle of the front wheel when the speed detected by the speed detector is lower than the threshold speed, and the value detected by the first detection device is equal to or greater than the predetermined value.   
     
     
         5 . The straddled vehicle according to  claim 4 , wherein
 the threshold speed is 40 km/h.   
     
     
         6 . The straddled vehicle according to  claim 1 , wherein
 the predetermined value is greater than an upper limit value of each of said at least one of the steering angular velocity of the front wheel, the acceleration of the steering angle of the front wheel, or the steering torque of the front wheel, with self-steering when the straddled vehicle turns on a curve.   
     
     
         7 . The straddled vehicle according to  claim 1 , wherein
 the controller determines that the detected value is greater than the predetermined value when a mean value of the steering angular velocity of the front wheel during a predetermined period is equal to or greater than the predetermined value, when a mean value of the acceleration of the steering angle of the front wheel during the predetermined period is equal to or greater than the predetermined value, or when a mean value of the steering torque of the front wheel during the predetermined period is equal to or greater than the predetermined value, and   the predetermined period is 0.2 seconds or less.   
     
     
         8 . The straddled vehicle according to  claim 1 , wherein
 the first detection device detects rotation of the steering device with respect to the vehicle body frame.   
     
     
         9 . The straddled vehicle according to  claim 1 , wherein
 the first detection device is a torque sensor that detects twist of the steering device.   
     
     
         10 . The straddled vehicle according to  claim 9 , wherein the steering device includes:
 front forks that support the front wheel,   a shaft member coupled to the front forks,   a handlebar coupled to the shaft member, and   the torque sensor detects a torque applied to the shaft member.   
     
     
         11 . The straddled vehicle according to  claim 1 , wherein
 the restriction device restricts rotation of the steering device with respect to the vehicle body frame.   
     
     
         12 . The straddled vehicle according to  claim 1 , wherein the restriction device includes a braking mechanism that applies a braking force for braking rotation of the steering device with respect to the vehicle body frame. 
     
     
         13 . The straddled vehicle according to  claim 12 , wherein the braking mechanism includes:
 an actuator that generates the braking force, and   a transmission mechanism that transmits the braking force from the actuator to the steering device.   
     
     
         14 . The straddled vehicle according to  claim 1 , wherein
 the restriction device is a steering damper that resists rotation of the steering device with respect to the vehicle body frame; and   the steering damper includes:
 a cylinder tube, 
 a piston that moves by hydraulic pressure in the cylinder tube, 
 a main shaft integrated with the piston, at least a tip end of the main shaft protruding from one end of the cylinder tube, and 
 a damping force adjustment device that is configured to, according to control by the controller, adjust the hydraulic pressure. 
   
     
     
         15 . The straddled vehicle according to  claim 14 , wherein
 the piston is installed inside the cylinder tube,   the cylinder tube includes a first chamber and a second chamber partitioned by the piston,   each of the first and second chambers has hydraulic oil stored therein,   the steering damper has a first path that communicates the first chamber and the second chamber,   the damping force adjustment device opens and closes the first path,   the damping force adjustment device closes the first path when the restriction device restricts the change in the steering angle of the front wheel, and   the damping force adjustment device opens the first path when the restriction device allows the change in the steering angle of the front wheel.